The main objectives of the ongoing project are to ascertain: whether the autonomic nervous system contributes to any extent to the physiological regulation of pancreatic glucagon secretion, since insulin secretion is known to be subject to some autonomic control, whether the changes induced in glucagon and insulin levels by sympathetic catecholamines and parasympathomimetic agents conform with the insulin- glucagon servomechanism proposed for humoral control of glucose homeostasis, wherein the insulinogenic effect of glucagon constitutes the positive loop, and the suppression of glucagon by insulin the negative loop, and whether the anomalous humoral situation of hyperglucagonemia -- non-suppressible by glucose -- recently recognized as characteristic of juvenile and maturity-onset diabetes mellitus (in addition to insulin lack or inadequate secretion) reflects modulation of normal autonomic influence on the insulin-glucagon servomechanism. Observations of changes in glucagon and insulin levels with the catecholamines, and during alpha- and Beta-adrenergic blockade, have been concluded, as has the examination of the effects induced by infusions of the cholinergic agents. The effects of cholinergic blockade will be completed. Alterations in the effects provoked by administration of the autonomic agents under conditions of hypoglycemic stress or experimental diabetes are to be examined.